1. Field of the Invention
The present invention relates to an assembly system for loading glass sheets of different size on a conveyor. When glass sheets are treated while conveyed on a conveyor, particularly of the roller type, it is desirable to load the sheets as closely as possible to one another while leaving some space to insure that the sheets do not bump into one another during their conveyance and cause chipping along the edges. Another reason for leaving some space between adjacent glass sheets occurs when the glass is thermally treated. It is necessary that the edges of the glass be separated so as to improve the heating uniformity throughout the extent of the glass sheet and if the glass sheets are subsequently cooled, it is also desirable to have some space around the edge of the glass to facilitate a more desirable pattern of cooling.
When glass sheets of uniform size are treated, consecutive sheets are loaded onto a conveyor by arranging the sheets so that their dimensions are correlated to the width of the conveyor and the rate of conveyor speed so that either a single sheet or a transversely extending row of glass sheets is loaded at a given interval of time to insure that the sheets are arranged with the proper longitudinal spacing commensurate with maximum loading per unit area of conveyor. However, when sheets of different size and/or outline shapes are mixed with one another for treatment, it becomes more difficult to load a conveyor efficiently. In a typical operation where glass sheets are conveyed to a furnace and brought to a temperature that is sufficient for subsequent treatment, such as quenching, coating, or other treatments required to fabricate a finished glass sheet further, as much as 50 percent or more of the area of the furnace has been wasted by loading sheets having a random size assortment consecutively onto a loading station at the entrance end of the furnace conveyor and periodically discharging the loading station.
It would be beneficial for the glass fabrication industry to improve the efficiency of operation. Until now, while the flat glass sheet industry has been able to improve the efficiency of cutting rectangular blanks into smaller sheets of different size and outline shape with minimum glass waste, it has been unable to improve the efficiency of operation of roller hearth furnaces when the furnaces were called upon to simultaneously treat glass sheets of different sizes and pattern outlines. This art needed technology that would make more efficient use of a treatment conveyor when the latter handles a variety of glass sheets having different sizes and/or outline shapes.
2. Description of Patents of Interest
U.S. Pat. No. 3,512,625 to Raynor et al. discloses an article accumulation and transfer apparatus comprising an article conveyor having a row forming section and a transfer section, wherein successive rows comprising a predetermined number of identical articles are formed at the row forming section and are transferred as a row to a transfer conveyor. The patented apparatus does not treat non-indentical articles.
U.S. Pat. No. 3,554,351 to Rothenback et al. discloses apparatus for lining up objects that are irregularly spaced along two or more rows. This apparatus is concerned with making combined packages each comprising objects from each row or from one of said rows.
U.S. Pat. No. 3,701,408 to Northsea discloses a method of handling boards of different dimensions while providing for exclusion of rejects. The acceptable boards are arranged in pairs or sets.
U.S. Pat. No. 3,762,907 to Quinn et al. refers to machines for forming hollow glass articles from molten glass where the operation is electronically controlled. The hollow glass articles that are formed are identical.
U.S. Pat. No. 3,905,793 to Croughwell discloses an improved machine for forming glassware over that of the Quinn et al patent. The improved system has digital computer control for making hollow glass articles.
U.S. Pat. No. 4,004,904 to Ferguson provides a system for identifying defective glass containers that are formed in a line and transferred from said line to successive rows for conveyance purposes. Means is provided to separate the defective glass containers so identified.
U.S. Pat. No. 4,073,387 to Bowser relates to forming a tier of many rows in such a manner as to avoid skewing of individual rows.
U.S. Pat. No. 4,120,403 to Stephanos relates to a photoelectric sensing apparatus to sense the size of different sized articles in a population of variegated articles and is provided with means for removing articles of different sizes onto different collection devices.
U.S. Pat. No. 4,157,408 to Lingl discloses a system for hacking glazed or unglazed tiles that accomplishes continuous hacking of either glazed or unglazed split tiles by feeding pallets into one or another of two conveyor systems without interrupting the tile manufacturing process.
U.S. Pat. No. 4,161,368 to Batzdorff discloses a brick blending apparatus wherein bricks having different characteristics are delivered to different staging areas in rows of spaced bricks and the rows are blended in a blending area to provide a blended array of bricks.
None of the patents cited relate to the present problem of forming groups of spaced glass sheets of different sizes and/or shapes that minimize waste area in a given area occupied by a diverse group that is to be transported along a conveyor through a treatment area.